key: cord-0928325-cnw660d5
authors: Chen, Zhongfei; Hao, Xinyue; Zhang, Xiaoyu; Chen, Fanglin
title: Have traffic restrictions improved air quality? A shock from COVID-19
date: 2020-08-13
journal: Journal of Cleaner Production
DOI: 10.1016/j.jclepro.2020.123622
sha: 739fcc396b39b3d37b05e1d1e365799649b73411
doc_id: 928325
cord_uid: cnw660d5

Abstract With the outbreak of COVID-19 (Corona Virus Disease 2019), China adopted traffic restrictions to reduce the spread of COVID-19. Using daily data before and after the outbreak of COVID-19, an exogenous shock, this paper analyzes the effects of private vehicle restriction policies on air pollution. We find that the private vehicle restriction policies reduce the degree of air pollution to a certain extent. However, their effect varies with other policies implemented in the same period and the economic development of the city itself. Through the analysis of different categories of restrictions, we find that restriction policy for local fuel vehicles and the restriction policy based on the last digit of license plate numbers have the best effect in reducing air pollution. Under the background of COVID-19 epidemic and the implementation of private vehicle restriction policies and other traffic control policies during this period, we have also obtained other enlightenment on air pollution control.

As air pollution has a significantly negative impact on economic development policies, adopted by many local governments after the outbreak of COVID-19, on air 39 pollution has been observed (Wang et al., 2020) . 40 To investigate the impact of the private vehicle restriction policy on air pollution 41 and to find reasonable ways to implement this policy to improve air quality, we The remainder of the paper is as follows. Section 2 describes the relevant studies. 74 Section 3 describes the data and econometric methodology. Next section provides the 75 baseline results and robustness check. Section 5 shows the heterogeneity analysis. 76 Section 6 discusses the conclusion of this study. The DID estimation technique allows us to control for omitted variables. We 202 include day-specific dummy variables to control for trends that shape the degree of air 

Our identification depends on the condition that air pollution does not lead to Observations 9,307 9,307 9,307 9,307 9,307 9,307 9,307

Notes: The coefficient estimates and standard errors related to meteorological characteristics are multiplied by 10,000 for readability. All 227 models control for city and day fixed effects. Robust standard errors are reported in parentheses. *, **, and *** indicate significance 228 levels at 10%, 5%, and 1%, respectively.

The Panel A results indicate that private vehicle restrictions substantially reduce Appendix Table 3 . The results in Table 2 and Appendix Table   260 3 are similar, suggesting that our results are not driven by the sample in the normal 261 period. where the restriction dummy variables, the "D's," equal 0, except as follows: D -j 268 equals 1 for cities on the j th day before restriction, while D +j equals 1 for cities on the 269 j th day after restriction. We exclude the day of the private vehicle restriction, thus Table 6 . 389 We find that, in addition to Hubei Province, the private vehicle restriction policies in Table 7 . 443 The results in Appendix Table 7 indicate there is no significant difference in the 444 effect of private vehicle restriction policies in cities with different population sizes. In 445 contrast, in cities with different levels of economic growth, significant differences are 446 observed in the effect of the restriction policies, which are reflected in the two 447 indicators of gross regional product and gross regional product growth rate. We find 448 that the restriction policies of private vehicles have a significant impact on air 449 pollution in the cities with low economic development levels. In the cities whose 450 gross regional product is less than 3.6×10 6 million yuan, the implementation of the 451 vehicle restriction policies induces a 23.6%, 32%, and 26% reduction in the 452 J o u r n a l P r e -p r o o f concentrations of AQI, PM 2.5 , and PM 10 , respectively, at the 5% significant level. 453 However, the results for the cities whose gross regional product are more than 

Due to the impact of the COVID-19, some cities decided to cancel private vehicle restriction to reduce the number of people who will 620 choice public transport, and some cities with more severe epidemics decided to resume private vehicle restriction in advance, in order to 621 reduce the number of people going out. As for suspension of public transport, some cities just reduce partial public transport. A blank 622 indicates that the relevant policy has not been implemented.

Wenzhou Zhejiang 

The observations do not contain control group. All models control for city and day fixed effects. Robust standard errors are reported 644 in parentheses. *, **, and *** indicate significance levels at 10%, 5%, and 1%, respectively. 

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